A communication network may include network elements that route packets through the network. Some network elements may include a distributed architecture, wherein packet processing may be distributed among several subsystems of the network element (e.g., line cards, switches, and traffic managers). In some instances, a network element used in a communication network may be a multi-function Ethernet aggregation network element. A multi-function Ethernet aggregation network element may be one which supports many functions, including without limitation link aggregation, virtual LAN (VLAN) detection, and traffic management/shaping.
In many instances, communication networks may employ link aggregation. Link aggregation (e.g., IEEE 802.1AX-2008) may generally describe the practice of using multiple network cables or ports in parallel to increase the link speed beyond the limits of any one single cable or port. Link aggregation may also be used to provide fault protection by increasing redundancy for higher availability. In link aggregation, a group or set of ports may be combined and represented as a single logical port to other components of the network system. Various switching elements of the network system may “see” the aggregated ports (known as a “link aggregation group” or “LAG”) as a single logical communication port in the routing tables or databases of network elements external to the LAG.
In addition, to ensure high reliability and availability in communications networks, protection switching is often used. When implemented, protection switching typically provides a primary or “working” path for a network and a redundant or “protection” path for the network. Accordingly, each path of a protection group may be monitored, and if a failure is detected on the working path, network traffic may be switched to the protection path. A LAG, because it includes a group of ports, may be used to perform protection switching. Other protection switching methodologies or protocols may also be employed in communication networks.
A multi-function Ethernet aggregation network element may include a distributed architecture including one or more plug-in units (PIUs). A PIU may comprise a modular electronic device that provides any suitable network communication functionality. For example, a PIU may include, among other things, an switch (e.g., an Ethernet switch) for switching traffic through the network element and a traffic manager for shaping and/or policing network flows.
In certain instances, PIUs may employ chip stacking, a hardware feature by which adjacent PIUs may interoperate by interconnecting chips of same type seamlessly using proprietary structure and protocols. Some PIUs may also support link aggregation and other protection switching schemes in hardware. However, a PIU supporting many hardware-based functions may be costly and have a relatively large physical footprint. Cost and size may be minimized by using PIUs not having such hardware-based features. However, without such hardware-based components, PIUs may not support stacking, protection switching, or other desirable features.